Multidetector computed tomography-derived left atrial wall thickness maps of patients undergoing persistent atrial fibrillation ablation

Abstract Funding Acknowledgements Type of funding sources: None. Background Pulmonary vein isolation (PVI) has proven to be effective in treating persistent atrial fibrillation (PeAF), although long-term ablation outcomes have been significantly less favorable than in paroxysmal AF. Purpose We sought to analyze multidetector computed tomography (MDCT)-derived left atrial wall thickness (LAWT) maps of patients undergoing PeAF radiofrequency ablation with a personalized approach aimed for adapting the ablation index (AI) of contiguous lesions to the local LAWT. Methods PeAF was defined in the presence of at least one AF episode sustained beyond 7 days, long-standing PeAF was defined as continuous AF of >12 months duration when decided to adopt a rhythm control strategy. For each patient included in the analysis, LAWT three-dimensional map were obtained from MDCT. LAWT was categorized into 1 mm layers and AI was titrated according to the LAWT. Results One hundred twenty-one patients (79.4% male, age 64.5±9.5 years) were included. Procedure time was 67 minutes (IQR 50-67), fluoroscopy time was 43 seconds (IQR 20-71), and radiofrequency time was 16.5 minutes (IQR 14.3-18.4). LAWT of the circumferential PV line was thicker in the LPVs as compared to the RPVs (1.64 mm [1.5-1.81] vs. 1.29 mm [1.16-1.57], p<0.01). More specifically, anterior wall segments were thicker in the LPVs as compared to the RPVs (2.1 mm [1.9-2.4] vs. 1.4 mm [1.1-1.9], p<0.01), while posterior wall segments had similar WT. Ablation index applied according to local LAWT was 387 (IQR 360-410) for the anterior wall and 335 (IQR 300-375) for the posterior wall. Overall first pass rate was 73.6%; median LAWT values were higher for PVs with no first pass during radiofrequency ablation with respect to the whole cohort (1.73 mm [1.57-1.98] vs. 1.64 mm [1.50-1.81] p=0.02 for LPVs; 1.46 mm [1.21-1.65] vs. 1.29 mm [1.16-1.57] p=0.03, for RPVs). LAWT values for each PV segment are represented in Figure 1. At a 12 months of follow-up the rate of recurrence-free survival was 79%. Recurrence-free survival rate was significantly higher in patients with PeAF with respect to those with long-standing PeAF diagnosis (p=0.044). A second ablation was performed in 18 patients out of those with AT/AF recurrence. Median LAWT values were higher for PVs with reconnection found in the redo procedures comparing to the median LAWT of the corresponding PVs of the whole cohort (1.77 mm [1.65-2.14] vs. 1.64 mm [1.50-1.81] p=0.01 for LPVs; 1.43 mm [1.25-1.61] vs. 1.29 mm [1.16-1.57] p=0.05, for RPVs). Methods and results are summarized in Figure 2. Conclusion This proof-of-concept study proves that personalized local LAWT-guided PVI ablation for PeAF is efficient and have good long-term outcomes. No first-pass segments during first procedure and reconnection sites within redo procedures were mostly found in thickest regions. A randomized trial comparing the LAWT-guided PVI with the standard of practice is in progress.